Multi-stage weight scale

ABSTRACT

A weight scale having an operational weighing range, comprising an overall response characteristic having at least first, second and third discrete stages over the operational weighing range. The first, second and third stages are defined by first, second and third predetermined response characteristics, respectively. The weight scale further comprises first, second and third scale arrangements or mechanisms which establish the first, second and third response characteristics, respectively, of the three stages.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation-in-part of Application Ser. No.09/354,740, filed Jul. 29, 1999.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to weighing scales, and is moreparticularly directed to a device for detecting and indicating changesin a small weight that is embedded within a much larger, i.e., heavier,residual weight.

[0003] It is difficult for the consumer to measure a small variableweight that is contained within a much larger weight, most of which is arelatively constant residual weight. It is also difficult to monitor andobtain an advance warning of the impending exhaustion of a givenvariable weight, which can be considered a critical weight.

[0004] A weight load can be considered to consist of two or morecomponents, that is, an initial part, a critical part, and an end part.The critical part is typically significantly smaller than either of theother two components, but this is typically the component whose weightis of the most interest. Consequently, any weighing device that detectsvariations, i.e., gradual depletion, of the critical component shouldhave a more sensitive scale for the critical part than for the other twoparts. In many cases, the consumer needs to monitor only the criticalpart, and the weighing device or scale only needs to read and monitorthe critical component, and not the initial or end parts.

[0005] A particular example of this is a cylinder of a consumable gas,such as propane or natural gas. The cylinder has an empty or residualweight which does not vary for that cylinder. Also, when completelyfilled with propane or natural gas, the cylinder has a full or initialweight, which also is a fixed value for that cylinder. The customer isinterested in monitoring the weight of the cylinder so that he or shewill be aware when the contents have been nearly consumed, and thecylinder is approaching an empty condition. Where the cylinder contains,for example, ten kilograms of propane, the consumer needs to know whenit has emptied down to about the final one or two kilograms, whichconstitute the “critical weight.” Consequently, the weighing scale needsto monitor only for that range of zero to two kilograms, which liessomewhere between the cylinder's residual weight and the cylinder's fullor initial weight. Thus, there is a need for a weighing device thatmonitors the critical part of the load.

[0006] There are many other applications as well, where the criticalpart of the load is embedded within the overall weight of the load,between the residual weight and the initial weight.

[0007] There may also be a need to monitor the fill, rather than thedepletion of a container's contents, in which case the critical weightwould be increasing instead of decreasing. The critical weight range canbe close to the initial weight instead of close to the residual weight.

OBJECTS AND SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of this invention to provide aweighing and monitoring technique that avoid the drawbacks of the priorart.

[0009] It is another object to provide a weighing scale of simple designwhich accurately monitors the critical part of the weight load.

[0010] It is yet another object to provide a weighing scale that can beadjusted for its range and sensitivity in measuring changes within thecritical weight range.

[0011] It is a further object to provide a weighing scale of ruggeddesign and which can provide an audible and/or visible alarm.

[0012] In accordance with an aspect of the present invention, anembedded weight scale indicates variations in weight of an articlewherein the variable weight is embedded within a heavier weight, andwhere the article has a base residual weight and a variable embeddedweight. The scale has a base with first and second upstanding walls anda top pan adapted for supporting the article whose weight is to bemonitored. There is a linkage, in this case formed of a pair of longlevers and a pair of short levers. The long levers each have a first endpivotally supported on the first wall of the base and a second end, thesecond ends being joined together by a pivot pin or the like. The shortlevers each have a first end pivotally supported on the second wall ofthe base, and each has a second end that is pivotally joined to amidpoint of a respective one of the long levers. The top pan issupported at four points, i.e., at a respective position on each of thelong levers and the short levers. There is a counterbalance pivot onsaid base, and this is preferably customer adjustable, i.e., by turninga wheel or screw. A counterbalance weight lever is joined at its firstend to the second ends of said long levers, and this lever extendsacross the base, over the counterbalance pivot, to a second end. Acounterbalance weight is supported on the second end of thiscounterbalance weight lever. The counterbalance weight lever has a rangeof movement that corresponds to the range of weight that includes theembedded weight, i.e., the critical weight, of the article.

[0013] An adjustable tensioning spring means permits the consumer toadjust the tension between the base and the long levers. Weightindicating means are also provided, including a sensor for sensingvariation in the position of the counterbalance weight lever as it moveswithin its range, i.e., within the critical weight range of the embeddedweight.

[0014] The weight indicating means may take the form of a potentiometerhaving a rotary slider, and a lever connecting the slider with thecounterbalance weight lever. A gear multiplier or other means can beemployed to increase the sensitivity range of the potentiometer.

[0015] The adjustable tensioning spring means can employ a spring holderplate affixed to said base, a spring tension adjusting screw on thespring holder plate, and a tensioning spring positioned between thespring holder plate and the second ends of the long levers.

[0016] The counterbalance weight may be selectively adjustable in itsposition on the counterbalance weight lever, so as to adjust thecritical weight range. Also, there are stops provided to limit themovement of the counterweight lever, with the positions of the stopsbeing selected to affect the selection of the critical weight range.

[0017] As can be understood, the range of counterbalance movement isgoverned by the height of the unit, and the positions of the stops,whereas the range of the critical weight is governed by the settings ofthe counterbalance weight, the counterbalance pivot, and the spring.

[0018] The above and many other objects, features, and advantages ofthis invention will become apparent to persons skilled in the art fromthe ensuing description of a preferred embodiment, which is to be readin conjunction with the accompanying Drawing.

BRIEF DESCRIPTION OF THE DRAWING

[0019]FIG. 1A is perspective view of an embedded weight scale monitoringunit and load, in the form of a cylinder of propane or liquefied naturalgas, according to an embodiment of this invention.

[0020]FIG. 1B shows the warning unit of this embodiment.

[0021]FIG. 2 is a schematic sectional elevation of the monitoring unitof this embodiment.

[0022]FIG. 3 is a schematic top view of this embodiment.

[0023]FIGS. 4A and 4B are schematic top plan and side views forexplaining the operation of this embodiment of this invention.

[0024]FIGS. 5A and 5B are charts for explaining the dependency ofcounterbalance weight.

[0025]FIGS. 6A and 6B are charts for explaining the dependency of springand stopper settings.

[0026]FIGS. 7A and 7B are charts for explaining sensitivity in thecritical weight range.

[0027]FIG. 8 is a graphical chart for explaining the general principlesof the counterbalance weight leverage system employed in thisembodiment.

[0028]FIG. 9 is a schematic side view of the counterbalance weight leverfor explaining this embodiment.

[0029]FIG. 10 is a top view of the counterbalance weight lever andsensor element of this embodiment.

[0030]FIG. 11 is an overall response characteristic of a Type Dembodiment of the present invention, showing three discrete stages.

[0031]FIG. 12A-12D are a series of overall response characteristics forTypes A, B, C and D embodiments, respectively, of the present invention.

[0032]FIG. 13 is a simplified schematic diagram of a Type B embodimentof the present invention.

[0033]FIG. 14 is a simplified schematic diagram of a Type C embodimentof the present invention.

[0034]FIG. 15 is a simplified schematic diagram of a Type D embodimentof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] With reference to the Drawing, an embodiment of the embeddedweight measuring weighing scale of this invention is shown in FIGS. 1Aand 1B. Here, a weighing scale device 10 has a rectangular or squarebase 12, and a top or weighing pan 14 supported over the base 12. A load16 is shown here to take the form of a gas cylinder, with a fill of acompressed consumable gas, such as propane or liquid natural gas. Thisis only an example, of course, and the load 16 can be any load that hasa basic, residual weight, and a larger total weight when filled. In thisembodiment the tank or cylinder 16 is shown with a partial remainingfill 18 (shown in ghost lines), with the contents being depleted andapproaching exhaustion. In this example, the empty weight of thecylinder or tank may be, for example ten KG, and the contents of thetank, when filled may be a similar weight, that is, another ten KG. Thecustomer is interested in being alerted when the tank is nearingexhaustion, that is, when there are about two KG of gas remaining insidethe cylinder 16. This last two KG of gas is considered the criticalweight in this example. That is, the cylinder has an initial (filled)weight of twenty KG, a residual (empty) weight of ten KG, and a criticalweight range between ten and twelve KG. A wire or cable 20 extends fromthe weighing or sensing unit 10 to an alarm or customer interface unit22, which is shown in FIG. 1B. The unit 22 may have an audible alarm toalert the consumer when the critical weight is detected, and may alsohave visible indicators, here a green lamp 26A which lights to indicatethat the weight is above the critical weight range, a yellow lamp 26B toprovide a warning when the weight has dropped into the critical range,and a red lamp 26C to provide a warning when the weight has droppedbelow the critical range, i.e., the propane or natural gas is exhausted.The unit 22 contains batteries and electronic circuitry, which are notshown here.

[0036] The construction of the weighing scale device 10 is illustratedin FIGS. 2 and 3. As shown, there is a linkage mechanism between thebase 12 and the top pan 14, in this case formed of a pair of long levers28 and a pair of short levers 30. The long levers 28 have one endpivoted on a back wall 32 of the base 12, and the short levers 30 haveone end pivoted on a front wall 34 of the base, with another endpressing down at the midpoints of the long levers 28, respectively. Thetop or pan 14 is shown to have four legs 36 that extend down and restupon locations along the long and short levers 28, 30, respectively.There is a pivot pin 38 through the second or free ends of the two longlevers 28.

[0037] A counterbalance weight lever 40 has one end attached to the longlevers at the pivot pin 38, and proceeds from there towards the backwall 32 of the base 12. A movable pivot 42 is positioned on the base 12and the lever 40 rests upon the pivot 42. A pivot adjusting screw 44,which is user actuable, permits the user to adjust the position of thepivot relative to the lever 40. A counterbalance weight 46 is positionedat the rear end of the counterbalance weight lever 40, and may beadjustable in its position along the lever. Shown near the front wall 34of the base 12 is a stopper 48 (which may be either factory-set orfield-adjustable) that limits the downward motion of the second ends ofthe long levers 28 and the front end of the counterbalance weight lever40.

[0038] An adjustable spring 50 is positioned at the second ends of thelong levers 28, and its tension is user-adjustable by means of a springtension adjusting screw 52. A spring holder plate 54 holds the spring inposition at the front wall 34 of the base, so that there is a springtension accorded between the base 12 and the counterbalance weight lever40. Also shown is a sensor element 56, e.g., a potentiometer, whichserves as an active detector and is sensitive to upwards or downwardsmotion of the counterbalance weight lever 40.

[0039] As shown in FIGS. 4A and 4B, the weight of the load 16, which istransmitted via the legs 36 to the long levers 28 and short levers 30,creates an image load or virtual load weight W_(L) at the position ofthe pivot pin 38, i.e., at the end of the counterbalance weight lever40. At the other end of the lever 40, the counterbalance weight has aweight W_(C). The pivot 42 is positioned to define a lever arm l betweenthe pivot and the virtual weight W_(L), and a counterbalance lever arm Lbetween the counterbalance weight 46 and the pivot 42. The virtualweight W_(L) depends on the actual weight of the load 16, and thevirtual weight W_(L) is in balance with the counterbalance weight W_(C)when this relation is satisfied: L×W_(C)=l×W_(L). When the load 16 isabove the critical range, the lever 40 is deflected to a maximum point ddetermined by the stopper 48. When the load weight drops into thecritical range, the virtual weight W_(L) is balanced by thecounterbalance weight W_(C), and the lever 40 moves through a deflectionrange D, i.e., until the counterbalance weight 46 bottoms out and restson the base 12. In this range, the lever 40 is free to move up and down,and changes in the virtual weight W_(L) are balanced by increasing ordecreasing the tension on the spring 50 under deflection of the lever40. The sensitivity in this range depends on the spring setting, whichthe user can adjust by means of the adjusting screw 52. The lengths ofthe lever arms L and l can be adjusted by moving the pivot 42, and alsoby moving the counterbalance weight 46. Also, the size of thecounterbalance weight 46 can be adjusted, i.e., by adding trim weights.

[0040] The initial weight value for the scale 10 can be set by adjustingthe counterbalance weight value, and its position on the lever 40, i.e.,from a relatively lower value x₀ to a higher value x₀′, as shown inFIGS. 5A and 5B. This does not affect the width of the critical range.The other bound of the critical range can be adjusted by adjusting thespring 50 and/or the stopper 48, i.e., from a relatively lower settingx₁ (FIG. 6A) to a relatively higher setting x₁′ (FIG. 6B). This canwiden or narrow the range of interest, i.e., the critical range. Thesensitivity to load weight variation within the critical range ofdeflection can depend on the sensitivity of the potentiometer 56, aswell as various mechanical parameters, such as the spring constant(stiffness) of the spring 50.

[0041]FIG. 8 is a chart for explaining the operation of the unit 10,i.e., calibrated to sense the critical weight range 18 of the propane ornatural gas cylinder 16 of FIG. 1. Here, the abscissa shows values ofload weight values, with X₀ corresponding to the residual weight, i.e.,the empty weight of the tank or cylinder 16; X_(RCW) corresponds to thecritical weight range, i.e., the final two KG 18 of propane or naturalgas in the cylinder, with X₁ being the upper limit of the criticalweight range X_(RCW). Above this is the residual weight range X_(RES),which is limited by the maximum rated weight X_(M) for the scale. Theexpected full weight of the cylinder 16 would be somewhat smaller thanthis value X_(M). Deflection of the counterbalance weight lever 40 isdepicted on the ordinate. This also corresponds to the scalesensitivity.

[0042] The stopper 48 blocks any deflection of the counterbalance weightlever 40 for weights in the range X_(RES), and the counterbalance weight46 is bottomed out in its range for load values at or below the residualvalue X₀. For loads in the critical range X_(RCW), the action of thespring 50 determines the deflection of the lever 40.

[0043] As shown in FIG. 9, a virtual load bearing point 58 is shown onthe counterbalance weight lever 40 to the right of the pivot 42. At theposition shown, the scale is at or below the residual weight, and thecounterbalance weight 46 is fully descended. The beginning of thecritical weight range, i.e., the value X₁, is characterized by the rightend of the lever 40 being descended into contact with the stopper 48.The weight values where these occur depends on the size of the weight 46and its position along the lever 40, and also on the position of thepivot 42. These depend to some extent as well on the stiffness of thespring 50, and its tension. Thus, the customer or user can field-adjustthe scale 10 to adjust the weight values in which an alarm or warning isreceived.

[0044] As shown in FIG. 10, the sensor element for this weighing scalecan be a potentiometer 56, here of the rotary type, with a rotor stem 60for moving the rotary wiper of the potentiometer. The rotor stem 60 hasattached to it a potentiometer lever arm 62, whose distal end is coupledto a mover element 64 on the lever 40, so that the potentiometer rotorstem 62 follows the up and down motion of the counterbalance weightlever 40. This can be mechanically arranged for optimal sensitivity. Inone possible arrangement, a planetary gear multiplier can be used toincrease the angular response of the potentiometer 56 to motion of thelever 40. Also, instead of a potentiometer, other devices may be used,such as a magnetic sensor (i.e., Hall device), optical indexer, or otherknown arrangement. Also, instead of the coil spring 50 shown here,another spring arrangement, e.g., a leaf spring or a torsion springcould be employed. In addition, the spring 50 could include an airbladder or other resilient means within the ambit of the presentinvention. The spring 50 may be positioned either above or below thelever 40.

[0045] Also, the scale need not have the square or rectangular shape asshown. Also, in some versions, rather than using the stopper 48 to limitthe motion of the lever 40, the lever 40 and the counterbalance weight46 can be limited in their upward direction by the height of the unit.

[0046] Well known systems, such as levers, hydraulics, springs andothers, are used to reduce, proportionally, the actual weight of a loadinto a fraction of that weight. Spring leverage systems and adjustablecounterbalance weight systems are the most commonly used, in ordinaryconsumer scales. It is a common practice in the art to use the leverageprinciples (or equivalent) in conjunction with either spring oradjustable counterbalance weight principles to obtain a scale weighingaction (i.e., “single action”).

[0047] In the preferred embodiment of the weighing scale of the presentinvention, a leverage system principle in combination with an adjustablecounterbalance weight principle is used for one stage of the scale'sweighing operation (hereinafter “counterbalance weight arrangement”); aleverage system principle in combination with a tension spring is usedfor another stage of the scale's weighing operation (hereinafter“leverage spring arrangement”); and another counterbalance weightarrangement is used to provide a third stage of the scale's weighingoperation. In the preferred embodiment of the present invention, the twoarrangements are incorporated to work together, independently, in threesequences, i.e., in three discrete stages. Thus, the present inventioncan be considered as three different scales, each one independent of theother, but working in sequence.

[0048] With reference to FIG. 11, an embodiment of the weight scale ofthe present invention will now be described. In the followingdescription, we start from zero load and end at full load. FIG. 11 showsa three-stage response over the operational range of the scale. In afirst stage, the scale will measure a constant or variable weight (forexample, an initial load) according to a predetermined units-vs.-weightcharacteristic or proportionality 102. In a second stage, the scale willmeasure a constant or variable weight (for example, critical load)according to another predetermined units-vs.-weight characteristic orproportionality 104. In a third stage, the scale will measure a constantor variable weight (for example, end load, maximum load, exhausted load,etc.) according to yet another predetermined units-vs.-weightcharacteristic or proportionality 106.

[0049]FIG. 11 shows characteristics 102, 104 and 106 as being linear;however, they may be a single value (a point), a constant (flat line),or a non-linear response. In the example shown in FIG. 11, the load isincreasing in all three stages. Of course, the scale function is thesame in either direction, whether the load is increasing or decreasing.It is apparent from the above description and FIG. 11 that the scale'soverall response is defined by three discrete responses or stages.

[0050] The embedded weight scale of the present invention can beconfigured in different types of embodiments. One embodiment, which werefer to as “Type A,” is suitable for a consumable gas cylinder or tankscale, the application described above with reference to FIGS. 1-10.Other types, which will be referred to as Types B, C and D, will bedescribed hereinbelow. The response characteristics (weight units vs.load weight) of Types A, B, C and D scales are shown in FIGS. 12A-12D,respectively. Again, the responses are from zero to full load.

[0051] In a Type A embodiment, a counterbalance weight arrangement and aleverage spring arrangement are utilized. An example of this embodimentis shown in FIGS. 2 and 9. Lever 40 is initially biased down bycounterbalance weight 46 (unbalanced), and needs a force W_(L) atbearing point 58 large enough to induce upwards movement of counterweight 46 (See FIG. 9). The magnitude of W_(L) is dependent on theweight of counterbalance weight 46, its distance from pivot point 42,and the distance of point 58 from pivot 42. These are the controllingfactors in determining a first stage R1 of the Type A scale's response(FIG. 12A). As shown in FIG. 12A, the response is zero units over firststage (or weight range) R1. At this stage, spring 50 is still under itspredetermined state of tension, and it will remain so until forced toexpand. Once lever 40 begins to move upwards (actuated by force W_(L) atpoint 58), spring 50 will begin to expand. This expansion marks thebeginning of a second stage R2 in the Type A embodiment (FIG. 12A). Thesecond stage continues until lever 40 hits stopper 48, at which point athird stage R3 in the scale's response begins (FIG. 12A). Third stage R3has a flat constant unit response, which may have an upper weight limitwhere the load at point 58 could damage or destroy the scale (i.e.,maximum mechanical limit).

[0052] With further reference to FIG. 12A, first stage R1 could be madesmaller or larger (i.e., varying W_(L)), according to the specificapplication, by altering one or more of the controlling factorsmentioned above. Second stage R2 can be altered by altering thespecifications of spring 50 and pre-tensioning spring 50 usingadjustment screw 52 (FIG. 2). Second stage R2 is limited by the distancelever 40 can travel without exceeding the expansion limitation of spring50. Stopper 48 is used to limit the lever travel distance in thisembodiment. Thus, in the second stage of a Type A scale, a criticalweight (or embedded weight), defined for a gas cylinder, can be measuredat a higher sensitivity (units-vs-weight proportionality) than the othervariable weights (weight ranges) associated with the gas cylinder. (Inthis example, the scale has a nil response as to these other variableweights). From this example, it is seen that three stages of weighing aload is obtained and controlled independently.

[0053] In a Type B embodiment, an adjustable counterbalance weightarrangement and a leverage spring arrangement are utilized. As shown inFIG. 12B, the scale of this embodiment also has a three-stageresponse—two linear responses (during a first and a second stage R1 andR2) and one nil response (during a third stage R3). A simplifiedschematic diagram of a Type B scale is shown in FIG. 13. FIG. 13represents a scale identical to that shown in FIG. 2, except that lever40 and counterbalance weight 46 have been replaced with a lever 140 andan adjustable counterbalance weight 146. Lever 140 is initiallymaintained in equilibrium over a pivot 142, and counter weight 146 isallowed to slide across lever 140 automatically (by means well known inthe art) to maintain the equilibrium (balance) of lever 140. This actiondefines the first stage (R1) of this embodiment (FIG. 12B).

[0054] Referring again to FIG. 13, when a load or force W_(L) is appliedat a virtual load bearing point 158, lever 140 is forced off balance,causing the system to re-adjust (or balance itself). Counterbalanceweight 146 slides to a new position until balance is re-established. Thesliding action of weight 146 will continue as load W_(L) increases, butultimately weight 146 will reach a limit and stop, as shown in brokenlines in FIG. 13. At this point, the first stage (R1) of the scale'sresponse ends and the second stage (R2) begins (FIG. 12B). A spring 150,like spring 50, comes into play during the second stage (R2). Duringstage R2, spring 150 expands until lever 140 hits a stopper 148. At thepoint when lever 140 hits stopper 148, the third stage (R3) begins.During stage R3, load W_(L) can increase up to an allowable maximummechanical limit for the scale. Stage R1 is altered by altering thedistance counter weight 146 is able to slide along lever 140 (d_(WC)),by changing the weight of counter weight 146, and by changing thedistance of bearing point 158 from pivot 142.

[0055] In a Type C embodiment, an adjustable counterbalance weightarrangement replaces stopper 48 in the Type A embodiment, and theremaining arrangements of the Type A embodiment are unchanged. Thus, theType C embodiment has a counterbalance weight arrangement, a leveragespring arrangement, and an adjustable counterbalance weight arrangement.The response for the Type C embodiment is shown in FIG. 12C. It hasthree stages—a nil response (during a first stage R1) and two linearresponses (during a second and a third stage R2 and R3). A simplifiedschematic diagram of a Type C scale is shown in FIG. 14. FIG. 14represents a scale identical to that shown in FIG. 2, except thatstopper 48 has been replaced with an adjustable counterbalance weightarrangement 248. The Type C embodiment of FIG. 14 further includes alever 240, a pivot 242, a counterbalance weight 246, a spring 250, and avirtual load bearing point 258.

[0056] In the Type C embodiment, the response of first stage R1 isidentical to the response of the first stage in the Type A embodiment(compare FIGS. 12A and 12C). The response of the second stage R2 isidentical to the response of the second stage in the Type A embodimentuntil lever 240 pushes down against adjustable counterbalance weightarrangement 248. Adjustable counterbalance weight arrangement 248functions in the same manner as the adjustable counterbalance weightarrangement described above with respect to the Type B embodiment.

[0057] As shown in FIG. 14, arrangement 248 includes a lever 248 a, aload bearing point 248 b, a counterweight 248 c, and a pivot 248 d. Theforce of lever 240 against bearing point 248 b causes an imbalance inlever 248 a. Counterbalance weight 248 c slides toward the left end(FIG. 14) of lever 248 a to reestablish balance or equilibrium of lever248 a. The displacement of counterbalance weight 248 c will eventuallybe limited by a stop at the end of lever 248 a or by the action of astopper (like stopper 48) located under the right side (FIG. 14) oflever 248 a. Of course, the responses of each of stages R1, R2 and R3can be altered as described above with respect to Type A and Bembodiments.

[0058] A Type D embodiment was already introduced with reference to FIG.11. A Type D embodiment is the fullest version of the present invention.It includes an adjustable counterbalance weight arrangement, a leveragespring arrangement, and another adjustable counterbalance weightarrangement. The response for the Type D embodiment is shown in FIG.12D. It has three stages R1, R2 and R3, with linear responses in eachstage. It functions like the Type B embodiment for the first two stagesand like the Type C embodiment for the third stage (compare FIGS. 12Band 12C with 12D). A simplified schematic diagram of the Type D scale isshown in FIG. 15. FIG. 15 represents a scale identical to that shown inFIG. 2, except that lever 40 and counterbalance weight 46 has beenreplaced with an adjustable counterbalance weight arrangement 340, 346,and stopper 48 has been replaced with an adjustable counterbalanceweight arrangement 348. The operation of the Type D embodiment of FIG.15 is self-evident in view of the descriptions of the Type B and Cembodiments.

[0059] Each one of the stages in a Type A, B, C or D embodiment may beequipped with its own controlling and sensing elements. These elementscan be of a conventional type, well known in the art, or especiallydesigned, depending on the particular weighing application.

[0060] It should now be understood that an appropriate proportionality(or sensitivity) and range can be predetermined for each operationalstage of the weight scale of the present invention.

[0061] While the preferred embodiments of the invention have beenparticularly described in the specification and illustrated in thedrawings, it should be understood that the invention is not so limited.Many modifications, equivalents and adaptations of the invention willbecome apparent to those skilled in the art without departing from thespirit and scope of the invention, as defined in the appended claims.

What I claim is:
 1. A weight scale including: an operational weighingrange; and an overall response characteristic having a plurality ofdiscrete stages over the operational weighing range, each stage beingdefined by a predetermined response characteristic.
 2. A weight scalehaving an operational weighing range, comprising: an overall responsecharacteristic having at least first and second discrete stages over theoperational weighing range, the first stage being defined by a firstpredetermined response characteristic and the second stage being definedby a second predetermined response characteristic; first scale means forestablishing the first response characteristic of the first stage; andsecond scale means for establishing the second response characteristicof the second stage.
 3. The weight scale of claim 2, wherein saidoverall response characteristic further includes a third discrete stagewithin its operational weighing range, the third stage being defined bya third predetermined response characteristic; and wherein said weightscale further comprises third scale means for establishing the thirdresponse characteristic of the third stage.